Q: A 20 kg block on a horizontal, frictionless surface is pushed and accelerates to 30 m/s from rest in 6 seconds. What is the magnitude of the applied force outward on the block?

$$F = ma = 20 \times \frac{30}{6} = 100\ \mathrm{N}$$

Q: A car of mass 1250 kg is moving at 20 m/s. The driver applies the brakes, resulting in a net force of 5000 N slowing the car down. How far does the car travel before stopping?

$$d = \frac{v^2$}{2a} = \frac{(20)^2$}{2 \times 4} = 32\ \mathrm{m}$$

Q: A 1000 kg rocket is taking off from rest, accelerating vertically upward. During the first 20 seconds, the force of gravity is 10,000 N downward, the engines provide 25,000 N upward, and air resistance is 5,000 N downward. What is the rocket's velocity after 20 s?

$$v = a t = \frac{25,000 - 10,000 - 5,000}{1000} \times 20 = 200\ \mathrm{m/s}$$

Q: A ball is thrown horizontally from a cliff with an initial speed of 10 m/s. If it takes 2 seconds to hit the ground, how far from the base of the cliff does it land?

$$d = v t = 10 \times 2 = 20\ \mathrm{m}$$

Q: A 2 kg object starts from rest and accelerates at $$4\ \mathrm{m/s^2$}$$ for 3 seconds. What is its final velocity?

$$v_f = v_i + a t = 0 + 4 \times 3 = 12\ \mathrm{m/s}$$

Q: A car accelerates from rest at $$2\ \mathrm{m/s^2$}$$ for 5 seconds. What is its final speed?

$$v_f = v_i + a t = 0 + 2 \times 5 = 10\ \mathrm{m/s}$$

Question 1

A 20 kg block on a horizontal, frictionless surface is pushed and accelerates to 30 m/s from rest in 6 seconds. What is the magnitude of the applied force outward on the block?

Accepted Answer

$$F = ma = 20 	imes \frac{30}{6} = 100\ \mathrm{N}$$

Question 2

Which equation correctly relates force, mass, and acceleration for linear motion?

Accepted Answer

$$F = m \cdot a$$

Question 3

A car of mass 1250 kg is moving at 20 m/s. The driver applies the brakes, resulting in a net force of 5000 N slowing the car down. How far does the car travel before stopping?

Accepted Answer

$$d = \frac{v^2$}{2a} = \frac{(20)^2$}{2 	imes 4} = 32\ \mathrm{m}$$

Question 4

Which of the following is NOT a variable in the Uniformly Accelerated Motion (UAM) equations?

Accepted Answer

Force ($$F)$$

Question 5

A 1000 kg rocket is taking off from rest, accelerating vertically upward. During the first 20 seconds, the force of gravity is 10,000 N downward, the engines provide 25,000 N upward, and air resistance is 5,000 N downward. What is the rocket's velocity after 20 s?

Accepted Answer

$$v = a t = \frac{25,000 - 10,000 - 5,000}{1000} 	imes 20 = 200\ \mathrm{m/s}$$

Question 6

Which step is NOT part of the recommended problem-solving strategy for force problems?

Accepted Answer

Guess the answer

Question 7

If a 5 kg object is acted upon by a net force of 15 N, what is its acceleration?

Accepted Answer

$$a = \frac{F}{m} = \frac{15}{5} = 3\ \mathrm{m/s^2$}$$

Question 8

Which of the following best describes the role of acceleration in force and motion problems?

Accepted Answer

Acceleration is the link between force and motion.

Question 9

A ball is thrown horizontally from a cliff with an initial speed of 10 m/s. If it takes 2 seconds to hit the ground, how far from the base of the cliff does it land?

Accepted Answer

$$d = v t = 10 	imes 2 = 20\ \mathrm{m}$$

Question 10

Which of the following is a correct Uniformly Accelerated Motion (UAM) equation?

Accepted Answer

$$v_f = v_i + a t$$

Question 11

A 2 kg object starts from rest and accelerates at $$4\ \mathrm{m/s^2$}$$ for 3 seconds. What is its final velocity?

Accepted Answer

$$v_f = v_i + a t = 0 + 4 	imes 3 = 12\ \mathrm{m/s}$$

Question 12

Which variable is NOT required to solve for displacement using the equation $$x = v_i t + \frac{1}{2} a t^2$?

Accepted Answer

Final velocity ($$v_f)$$

Question 13

A car accelerates from rest at $$2\ \mathrm{m/s^2$}$$ for 5 seconds. What is its final speed?

Accepted Answer

$$v_f = v_i + a t = 0 + 2 	imes 5 = 10\ \mathrm{m/s}$$

Question 14

Which of the following is a correct step when solving a force and motion problem involving multiple forces?

Accepted Answer

Sum all forces to find net force before applying $$F = ma$$

Question 15

A 10 kg box is pulled with a force of 50 N on a frictionless surface. What is its acceleration?

Accepted Answer

$$a = \frac{F}{m} = \frac{50}{10} = 5\ \mathrm{m/s^2$}$$

Question 16

Which equation would you use to find the final velocity of an object given its initial velocity, acceleration, and time?

Accepted Answer

$$v_f = v_i + a t$$

Question 17

A 3 kg object is moving at 6 m/s. If a net force of 9 N acts on it for 2 seconds, what is its final velocity?

Accepted Answer

$$v_f = v_i + a t = 6 + \frac{9}{3} 	imes 2 = 12\ \mathrm{m/s}$$

Question 18

Which of the following is a correct application of the UAM equation $$v_f^2$ = v_i^2$ + 2 a x$$?

Accepted Answer

To find the final speed of a car after traveling a certain distance under constant acceleration

Forces, Motion Variables, and UAM Equations in Physics

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